Corrugated paperboard is typically used in many different applications, for example, to form containers, boxes, cartons, or dividers for holding, storing, stacking or shipping various items such as agricultural produce.
Typically, such containers have a bottom and four sidewalls, and are formed from a blank scored with score lines or cut lines. The blanks are most often formed by automated machines in a continuous in-line process involving cutting, scoring and molding continuous sheets of paperboard. The paperboard is then folded along the score lines or cut lines to form a container. The blanks may be folded into a container by an automated machine or by a consumer.
During use, containers are often stacked on top of one another for ease of shipping and for optimum use of space. In these circumstances, it is possible for containers to have stacking tabs extending upward from the top edge of the container's sidewalls. These stacking tabs often fit into corresponding notches cut into an adjacently stacked container to help secure the stack. Since containers are usually stacked on top of like sized containers, the stacking tabs that extend upward from a lower container's sidewalls position directly into the sidewalls of a higher, adjacent container. Thus, to accommodate the lower container's tabs, a complementary notch must be cut out of the higher container's sidewalls. However, a notch in a sidewall is problematic in that it does not secure the stacking tab on all four sides. Thus, these sidewall notches do not fully prevent side-to-side movement, subjecting the stack to potential toppling. This is sometimes circumvented by having a multi-ply or multi-layer sidewall, wherein a stacking tab extends upwards from an inner layer of the sidewall, thereby aligning the stacking tabs with the bottom panel of an adjacent container as opposed to the sidewall. This, however, requires excess paperboard to be used to create the multi-layer sidewall, and results in related increased costs.
Further, it is easy to misalign a container during stacking such that a higher container falls into a lower container, usually on an angle, potentially damaging the contents of the lower container. To solve this, several prior art patents have devised tapered sidewalls, wherein the distance between the opposing top edges of the sidewalls is less than the distance between the opposing lower edges of the sidewalls. This eases stacking by severely limiting the probability of the higher container falling into a lower container, since the narrower upper portion creates a more functional ledge for the base of the higher container to rest on.
Therefore, it is an object of this invention to provide a paperboard container with a stacking structure that has tapered sidewalls and stacking tabs, resulting in a narrower top footprint than the bottom footprint, and wherein the stacking tabs are secured on all four sides by an adjacently stacked container.
Still further, diagonally extending reinforcing corner panels are sometimes provided on conventional containers to reinforce the container and assist in preventing an upper container from falling into a lower container when they are stacked. The diagonal corner panels or posts in these containers extend the full height of the container, and therefore require additional material and concomitant increased cost to form.
Accordingly, it is a further object of this invention to provide reinforcing structure at the top edges of the container, using a minimum amount of material, and defining panels extending diagonally across only an upper portion of the corners of the container to reinforce it and provide structure that assists in preventing an upper container from falling into a lower container when they are stacked.